Angiotensin converting enzyme inhibitors (ACEi) and 5-HT.sub.3 (5-hydroxytryptamine.sub.3) receptor antagonists have previously been shown to improve the basal performance of laboratory animals in habituation paradigms and also to overcome the impairment induced by scopolamine (Costall et al (1989), "The effects of ACE inhibitors captopril and SQ29,852 in rodent tests of cognition." Pharmacol. Biochem. Behav. 33; 573-579; Barnes, J. M., et aI (1990), "The effects of ondansetron, 5-HT.sub.3 receptor antagonist, on cognition in rodents and primates." Pharmacol. Biochem. Behav. (35; 955-961).
U.S. Pat. Nos. 4,046,889 and 4,105,776 to Ondetti et al discloses proline derivatives, including captopril, which are angiotensin converting enzyme (ACE) inhibitors useful for treating hypertension.
U.S. Pat. No. 4,337,201 to Petrillo discloses phosphinylalkanoyl substituted prolines, including fosinopril, which are ACE inhibitors useful for treating hypertension.
U.S. Pat. No. 4,374,829 discloses carboxyalkyl dipeptide derivatives, including enalapril, which are ACE inhibitors useful for treating hypertension.
U.S. Pat. No. 4,452,790 to Karanewsky et al, discloses phosphonate substituted amino or imino acids and salts thereof and covers (S)-1-[6-amino-2-[[hydroxy(4-phenylbutyl)-phosphinyl]oxy]-1-oxohexyl]-L-pr oline (ceranapril, SQ 29,852). These compounds are ACE inhibitors useful in treating hypertension.
U.S. Pat. No. 4,316,960 to Ondetti et al, discloses ether and thioether mercaptoacyl prolines which are ACE inhibitors useful in treating hypertension. This Ondetti et al patent covers zofenopril.
U.S. Pat. No. 4,931,430 to Sudilovsky et al, discloses a method for preventing or treating anxiety employing an ACE inhibitor in combination with a calcium channel blocker.